Knowledge sharing on metal-bonded diamond tools

Answer:

• ① Using metal-coated diamond varieties
• ② Selecting metal binders that can wet the diamond surface

• Iron: An appropriate proportion will keep the sintering temperature of the binder below 900°C.
• Cobalt: Provides good bonding strength to diamond, adjusts the hardness of the matrix, offers good wear resistance, and is impact resistant.
• Copper: Bronze binders have lower hardness, poor wear resistance, and weaker bonding to diamond.
• Tin: When mixed with copper powder, it reduces the bonding to diamond.
• Titanium: Has good wettability to diamond, thus providing good bonding to diamond.

Answer:

The sintering temperature of Cu-Sn binary alloy bonded diamond abrasives is generally 650-700°C. When high-melting-point metals are added to the binder, the sintering temperature can be appropriately increased, but it is generally not desirable to exceed 800°C. However, for short-time sintering and when using high-quality diamond abrasives, the sintering temperature can be increased. For grinding wheels, the temperature can be raised to above 800°C, and for saw blades and drill bits, it can be raised to 900°C or even above 1000°C. The sintering temperature can be determined experimentally or by using a temperature 40°C lower than the temperature at which surface deformation and pitting begin to appear.

Answer:

① Adhesive wear: Diamonds adhere to the stone surface, and particles are sheared off;

② Abrasive wear: Many hard points on the rock scratch the diamond surface;

③ Diffusion wear: Chemical interaction between the rock and the diamond surface reduces the strength and hardness of the diamond, leading to increased wear.

Answer:

When the grinding speed increases, the total wear decreases. Wear reaches a minimum at a critical speed Vo. When the speed continues to increase beyond Vo, wear begins to increase slowly.

Answer:

Adding a certain amount of WC to the binder results in higher hardness and better wear resistance. Strict control of the hot pressing and sintering process is crucial to avoid situations where the matrix density is significantly lower than the theoretical value due to excessively high or low temperatures, insufficient pressure, etc., leading to increased porosity and decreased strength.

Answer:

① Rare earth elements can effectively lower the melting point of the alloy.

② Cerium (Ce) has strong deoxidizing, denitrogenizing, and desulfurizing effects, and can inhibit the segregation of oxygen, nitrogen, and sulfur.

③ It can reduce the contact angle of the liquid alloy with graphite.

④ Cerium has a significant grain refining effect on the alloy.

⑤ The addition of rare earth elements changes the mechanical properties of the matrix.

⑥ Rare earth elements affect the interface conditions.

⑦ It improves the microstructure of the matrix alloy.